This invention relates to an apparatus and method for an assembly and a disassembly of interchangeable surgical acoustic members. More particularly, this invention relates to a fixture for securing a surgical handpiece for cooperating with a torquing wrench having a tightening head with predetermined torquing limits and a loosening head mounted on the same body. Still more particularly, this invention relates to a method of assembling and disassembling such interchangeable surgical acoustical members.
Ultrasonic surgical devices are known for performing a number of surgical procedures. A representative device is shown in U.S. Pat. No. 3,589,363 describing a hand-held instrument having an operative tip vibrating at a frequency in the ultrasonic range, and in which a handpiece includes a transducer. Connections are provided on the handpiece to a source of treatment fluid and a pump to withdraw suspended tissue particles in a fluid from an operative site. The tip is elongated and provided with a thickened shank portion formed with a pair of flats, originally intended to accommodate a wrench for tightening.
In practice, the design of such ultrasonic surgical devices depends not only on the technical and functional requirements of a resonant body, but also upon its surgical application. Thus, the length of the tip and its diameter to be acceptable for a useful surgical device in various operative site areas has developed over the years, based upon experience with such devices. In particular, it has been determined in the art that an especially useful arrangement incorporating proportioned surgical acoustic members, both from the standpoint of its surgical application and with respect to its manufacturability and costs, is based upon a combination of parts that are threaded together for easy interchange. The joint between the tip and the device is generally made at a point between a half-wave and quarter-wave length of the acoustic member in question.
However, as the length of the interchangeable part approaches a quarter wavelength, the stress at the threaded joint increases, thus requiring a greater force to maintain the coupling surfaces in appropriate contact during ultrasonic vibrations. In practice, it is important for intimate contact to be maintained between the coupling surfaces to maximize energy transfer, minimize mechanical losses, obtain consistent performance during surgical use of the device, and to minimize parasitic vibrations during operation. In particular, the latter may cause premature failure of either or both of the coupled acoustic members.
Experience with such devices has also determined an appropriate coupling force or torque for such systems. The coupling torque is sufficiently great that the acoustic members cannot be adequately fastened with normal finger force, requiring a wrench with an appropriate mechanical advantage. Thus, a technique for fastening and unfastening such surgical tips to such devices has been available to the art, as will be described in greater detail.
The techniques of fastening and unfastening the surgical tip to the device are based upon a number of constraints in the art. On the one hand, the design and size of the threaded joint between the tip and the acoustical member is made as small as possible to minimize the weight for the surgeon and to minimize visual interference with the surgical procedure. Partly because of such size, overtightening of the threaded joint is not desirable since overtightening may overstress the threaded joint resulting in its fracture. On the contrary, insufficient tightening can result in incomplete acoustical coupling, heating of the threaded joint, degraded surgical performance, and a potential for eventual catastrophic failure of the acoustic parts.
A system available to the art, which will be described in connection with FIGS. 1 and 2, has provided two torque wrenches, a tip socket, a stack socket and a holding fixture to provide operating room personnel with an ability to secure the handpiece of the surgical device, tighten the tip to the handpiece to a preset level, and then later untighten the interchangeable acoustic members used for each surgical case. Such an apparatus used a conventional tightening wrench, but some difficulty was experienced in providing enough force to loosen the ultrasonic tip after a surgical usage. Accordingly, a second wrench, for untightening, was provided as an adapted commercial device allowing disassembly of the acoustic members without allowing uncontrolled tightening by the use of a single direction clutch. Such an apparatus was intended for use in a non-sterile field and somewhat cumbersome as surgical devices developed to include curved and straight extenders. The availability of alternative tip structures for use by the surgeon resulted in a more elaborate and more complex device which is difficult and confusing to utilize, was not easily portable, and tended to be expensive to manufacture. In addition, such device was not readily sterilizable for use in an operative field for the convenience of changing tips during surgery.
Accordingly, it was a problem in the use of such a device to develop a simplified torque wrench to combine the tightening and loosening features in a single wrench, capable in this environment of cooperating with an existing handpiece holding fixture. One particular problem was that socket wrenches which were commercially available were not readily useable on elongated members because the available sockets are solid and not suited for use at a position intermediate an elongated member.
Accordingly, it is an overall object of this invention to provide a modified fixture for securing the handpiece of the surgical device for tightening and loosening a surgical tip secured to the handpiece.
It is another overall object of the invention to provide such a handpiece fixture which can be hand-held or readily mounted on a stand on a table to support the handpiece and handpiece fixture during assembly or disassembly.
It is still another object of the invention to provide such a handpiece fixture which is capable of accepting in a rotatably secure position various handpiece and tip combinations, such as are comprised by a standard straight handpiece or an angled handpiece, on the one hand, connected directly to straight, curved or flexible tips, or to straight or curved extenders to which the tip is attached.
It is still another object of the invention to provide such a fixture for a handpiece of the type described, wherein the relative rotation between the fixture, a handpiece, and the acoustic vibrator can be secured to a key as in the currently commercial embodiment so that the fixture and wrench according to this invention can be utilized with existing surgical devices and handpieces currently available to operating personnel.
It is another overall object of this invention to provide a convenient method and apparatus to facilitate a change in the fragmenting and related elements during a surgical procedure in a way which eliminates a need for removing the acoustic vibrator from the handpiece as in the prior art.
It is still another overall object of this invention to provide a torque wrench which is capable of sliding over an assembled and hand-tightened combination of a handpiece, tip, and/or extender and to provide a socket which is structurally accommodated to such an elongated subassembly.
It is still another object of this invention to provide a torque wrench with a socket assembly of the type described having both a tightening head preset to a predetermined torquing limit and a loosening head, arranged in such a way to preclude an operator from applying the wrench in an erroneous direction.
It is still another object of this invention to provide a fixture for use with such a wrench that can be used in hand to cooperate with the wrench in a scissor fashion, or be supported on a table support plate at the choice of the user.
It is a further overall object of this invention to provide such a handpiece torquing set in kit form for the convenience of medical personnel and arranged for easy sterilization within the sterile field so that the tips can be quickly and easily exchanged either prior to, during or after surgery with a minimum disassembly of the handpiece, while avoiding inadvertent damage to the exposed acoustic vibrator stack and human engineered to minimize operator error and confusion.